Papers by Author: Zheng Leng

Abstract: Concrete with a compressive strength of 100MPa was produced with metakaolin(MK), and the effect of MK replacement levels on compressive strength of concrete with a water to binder ratio of 0.25 was studied in this paper. XRD, microhardness tests, SEM and MIP were used to investigate the influences of MK on the phase composition, microhardness of interfacial transition zone(ITZ), microstructural morphology and pore structure of the high-strength concrete (HSC). The results showed that the incorporation of MK promoted the hydration process and decreased the amount of Ca(OH)2 crystals. Furthermore, MK increased the ITZ microhardness of HSC, enhanced the hydrates and improved the bond performance of aggregate and paste. The weak zone between aggregate and paste became almost disappeared when 10% MK was blended. Meanwhile, refinement of the concrete pore structure was obtained in the presence of MK. The improvement of strength and microstructure became more obvious as the MK replacement level increased to 15%.

Abstract: The experimental study was performed on the relationship between the mechanical and durability properties of high-strength concrete with metakaolin (MK) and slag. The compressive strength, chloride penetrability and pore structure of the OPC and the concrete with MK and slag were measured. It is found that MK can significantly increase the compressive strength, decrease the chloride ions migration coefficient and improve the pore structure of the steam cured high-strength concrete. The chloride resistance is improved obviously by 5% MK and further increase of the MK dosage performs a little change of the chloride migration coefficient. Better improvement effect on the mechanical and durability properties is obtained with the incorporation of 10% MK and 10% slag. Linear relationship is found between the coarse pore porosity and the compressive strength, while the chloride migration coefficient correlates well with the capillary pore volume.